Diaphragmatic hypoplasia is a diagnostic imaging sign of emphysema, lung abscess, or tracheal foreign body on lung x-ray. Its etiology is commonly due to emphysema, lung abscess or tracheal foreign body. Emphysema is a common cause of diaphragmatic hypoplasia, a pathological condition in which the airways at the distal end of the terminal fine bronchi (respiratory fine bronchi, alveolar ducts, alveolar sacs and alveoli) are hypoelastic, hyperinflated, inflated and have increased lung volume or are accompanied by airway wall destruction. Early emphysema may be asymptomatic or may be characterized by shortness of breath during labor or exercise, with gradual difficulty in performing the original work. As the emphysema progresses, the degree of dyspnea increases, so that shortness of breath is still felt even after a little activity or even at complete rest. In addition, they may also feel weak, lose weight, lose appetite, and feel full in the upper abdomen. The main cause of emphysema is chronic bronchitis, so in addition to shortness of breath, there are also symptoms such as cough and sputum, and in the early stage, there is only prolonged expiratory phase or no abnormalities. In typical emphysema, the anteroposterior diameter of the thorax is enlarged, barrel-shaped chest, respiratory motion is reduced, voice tremor is diminished, percussion is over clear, heart turbid boundary is narrowed, liver turbid boundary is shifted down, breath sounds are reduced, sometimes dry and wet rales can be heard, heart rate is increased, heart sounds are low and distant, and the second heart sound of pulmonary artery is hyperactive. Diagnosis The diagnosis of scientific research can be made based on history, physical examination, X-ray examination and pulmonary function measurements. Pulmonary function measurements show increased residual air and total lung volume, increased residual air/total lung volume ratio, significantly decreased 1-second rate, and decreased diffusion function. Differential diagnosis The differential diagnosis of emphysema from tuberculosis, lung tumors and occupational lung diseases should be noted. In addition, chronic bronchitis, bronchial asthma and obstructive emphysema are all chronic obstructive pulmonary diseases, and both chronic bronchitis and bronchial asthma can be complicated by obstructive emphysema. However, the three are both related and different and cannot be equated. Chronic bronchitis is mainly limited to the bronchial tubes before the complication of emphysema, and there may be obstructive ventilation disorder, but the degree is mild, and the diffusion function is generally normal. During the exacerbation of bronchial asthma, there is obstructive ventilation and hyperinflation of the lungs, and gas distribution can be severely uneven. However, these changes are more reversible and respond better to inhaled bronchodilators. Diffusion dysfunction is also not obvious. Moreover, bronchial asthma is characterized by significantly higher airway reactivity and large diurnal fluctuations in lung function.